Grafted EVA particles and their preparation method, pre-connected grafted EVA film and its preparation process, and lamination process of laminated glass

Abstract

The present application relates to the field of EVA modification technology, and specifically discloses a grafted EVA particle and a preparation method thereof, a pre-crosslinked grafted EVA film and a preparation process thereof, and a laminated glass lamination process. The raw materials of the grafted EVA particles include EVA, a grafting initiator, and a hydrophilic modifier; the preparation method of the grafted EVA particles is: after mixing the raw materials, add them to a screw extruder for melt extrusion and granulation; the raw materials of the pre-crosslinked grafted EVA film include grafted EVA particles, a photoinitiator, a co-crosslinking agent, and a silane coupling agent; the preparation process of the pre-crosslinked grafted EVA film is: after mixing the raw materials, add them to a screw extruder, extrude through a T-shaped flat die, cast, cool and shape after shaping, and then irradiate; the laminated glass lamination process is: vacuuming the interior of the laminated glass to be treated, heating and maintaining the temperature at 80-120°C to obtain the laminated glass after vacuum heating. The present application has the effect of improving the defect that EVA has poor hydrophilicity, which leads to the generation of fog easily after water vapor enters the laminated glass.

Description

Technical Field

[0001] The present application relates to the field of EVA modification technology, and in particular to a grafted EVA particle and a preparation method thereof, a pre-crosslinked grafted EVA film and a preparation process thereof, and a laminated glass lamination process. Background Art

[0002] Ethylene-vinyl acetate copolymer (EVA) is a common polymer, with the weight percentage of vinyl acetate (VA) typically ranging from 5% to 40%. Compared to polyethylene, EVA incorporates VA monomers into its molecular chain, which reduces crystallinity while improving properties such as flexibility, impact resistance, and heat sealing.

[0003] The performance of EVA resin is closely related to the VA content in the molecular chain. Generally speaking, the higher the VA monomer content, the higher the transparency and flexibility of the EVA resin will be. Depending on the VA content, EVA resin can be made into different products and is widely used in various fields.

[0004] EVA film is a highly versatile EVA product with adhesive and thermosetting properties. It is commonly used in the lamination process of glass to provide an adhesive bond. Due to its excellent durability, adhesion, and optical properties, EVA film is gaining increasing popularity. However, during wet heat aging testing of laminated glass made with EVA film after assembly, moisture enters the glass edges. Due to EVA's poor hydrophilicity, the moisture separates from the EVA and aggregates to form dispersed droplets, creating a non-transparent or translucent fogged state at the edges of the laminated glass, affecting its normal use. Therefore, how to improve the defect of fogging at the edges of laminated glass is an important topic that requires urgent research. Summary of the Invention

[0005] In order to improve the defect of poor hydrophilicity of EVA, which leads to the generation of fog after water vapor enters the laminated glass, the present application provides a grafted EVA particle and a preparation method thereof, a pre-cross-linked grafted EVA film and a preparation process thereof, and a laminated glass lamination process.

[0006] In a first aspect, the present application provides a grafted EVA particle, which adopts the following technical solution:

[0007] A grafted EVA particle comprises the following raw materials in parts by weight:

[0008] EVA 100 pieces

[0009] Graft initiator 0.01-0.1 parts

[0010] 0.5-5 parts of hydrophilic modifier

[0011] The hydrophilic modifier is represented by the following chemical formula 1:

[0012] Chemical formula one:

[0013] Wherein, X1 is one of a hydrogen atom, a methyl group, and an ethyl group; X2 is a C1-C6 divalent hydrocarbon group; X2 can be a linear divalent hydrocarbon group or a branched divalent hydrocarbon group; X2 can be a saturated divalent hydrocarbon group or an unsaturated divalent hydrocarbon group; and R is selected from one of the following groups:

[0014] (1) R is one of carboxyl, sulfonic acid and hydroxyl groups;

[0015] Or (2) R is represented by the following chemical formula 2:

[0016] Chemical formula 2:

[0017] wherein Y1 and Y2 are the same or different and are each independently selected from one of a hydrogen atom, a methyl group and an ethyl group;

[0018] Or (3) R is represented by the following chemical formula 3:

[0019] Chemical formula 3:

[0020] Or (4) R is represented by the following chemical formula 4:

[0021] Chemical formula 4:

[0022] Wherein, Z is one of chlorine, bromine and iodine.

[0023] By adopting the above technical solution, under the action of a grafting initiator, EVA and a hydrophilic modifier undergo a grafting reaction, introducing hydrophilic groups into the molecular chains of the EVA. The hydrophilically modified grafted EVA particles are then made into a grafted EVA film, which is then applied to laminated glass. When water vapor enters from the edge of the glass, the hydrophilic groups introduced into the EVA molecules can combine with the water molecules, making it difficult for the water vapor in the laminated glass to aggregate into droplets, thereby improving the defect of easy fogging at the edge of the laminated glass.

[0024] The mass ratio of the hydrophilic modifier to EVA is set at 0.5%-5%, and the mass ratio of the grafting initiator to EVA is set at 0.01%-0.1%. Under this ratio, the grafting rate of the EVA molecules can reach 0.1%-5%. The grafted EVA film made of grafted EVA particles with this grafting rate can effectively improve the problem of fogging at the edge of the laminated glass when used in laminated glass. If the feeding amount of the hydrophilic modifier and the grafting initiator is further increased, although the grafting rate of the EVA molecules can be correspondingly increased, there is no significant improvement in the anti-fog performance of the laminated glass, but it is likely to lead to increased costs and waste of resources.

[0025] Optionally, X2 is a saturated divalent hydrocarbon group.

[0026] By adopting the above technical solution, X2 is limited to a saturated hydrocarbon group, so that there is only one carbon-carbon double bond on the molecular chain of the hydrophilic modifier. During the grafting reaction, it is not easy for a three-dimensional cross-linking reaction to occur in the system, so that the fluidity of the grafted EVA film made of grafted EVA particles is higher, and the possibility of the fluidity of the grafted EVA film decreasing due to three-dimensional cross-linking between EVA and the hydrophilic modifier is reduced.

[0027] Optionally, the grafting initiator is a vulcanizing agent DCP or a vulcanizing agent bis-25 or a mixture of the two.

[0028] By adopting the above technical solution, the grafting reaction temperature of EVA is usually higher than 100°C. The vulcanizing agent DCP and the vulcanizing agent bis-25 are both grafting initiators with high activation energy and appropriate half-life at this temperature, making the grafting reaction efficient, stable and controllable.

[0029] Optionally, the mass percentage of VA in the EVA is 18%-40%.

[0030] By adopting the above technical solution, EVA with a VA content greater than 18% has good fluidity under processing conditions, which is convenient for subsequent preparation of a grafted EVA film. The grafted EVA film has high fluidity and is convenient for lamination with glass.

[0031] Optionally, the mass percentage of VA in the EVA is 25%-33%.

[0032] By adopting the above technical solution, when the VA content is within the range of 25%-33%, the EVA resin has higher transparency, higher fluidity and softness, thereby improving the performance of laminated glass made of grafted EVA film.

[0033] In a second aspect, the present application provides a method for preparing grafted EVA particles, which adopts the following technical solution:

[0034] A method for preparing grafted EVA particles comprises the following steps:

[0035] S1. Prepare raw materials according to the ratio, stir and mix EVA, grafting initiator and hydrophilic modifier to obtain mixture A;

[0036] S2. Adding mixture A into a screw extruder for melt blending, extrusion, and granulation to obtain grafted EVA particles.

[0037] By adopting the above technical solution, the raw materials are stirred and mixed and then granulated through a screw extruder to obtain hydrophilic modified grafted EVA particles, which are convenient for subsequent preparation of grafted EVA films and application in the glass lamination process to improve the defect of fogging easily generated at the edges of laminated glass.

[0038] Optionally, in step S2, the temperature of the screw extruder is controlled at 160-180° C., and the screw speed of the screw extruder is controlled at 160-180 r / min.

[0039] By adopting the above technical solution, when the granulation temperature is controlled within the range of 160-180° C., the grafting reaction efficiency of EVA is high, the grafting initiator is not easy to volatilize, and the obtained grafted EVA particles have better performance.

[0040] In a third aspect, the present application provides a pre-crosslinked grafted EVA film, which adopts the following technical solution:

[0041] A pre-crosslinked grafted EVA film comprises the following raw materials in parts by weight:

[0042] 100 parts of grafted EVA particles

[0043] Photoinitiator 0-5 parts

[0044] 0.1-2 parts of cross-linking agent

[0045] Silane coupling agent 0.1-1 part.

[0046] By adopting the above technical solution, the co-crosslinking agent is conducive to promoting the cross-linking reaction between the grafted EVA molecules, and the silane coupling agent is conducive to improving the adhesive properties of the pre-crosslinked grafted EVA film, thereby improving the strength of the laminated glass;

[0047] Through the cross-linking reaction, the grafted EVA film has a certain degree of cross-linking, which on the one hand improves the stability and weather resistance of the grafted EVA film. When used in the lamination process of laminated glass, the size and shape of the pre-cross-linked grafted EVA film are not easy to change, thereby reducing the defective rate of laminated glass. On the other hand, by controlling the pre-cross-linking degree, the pre-cross-linked grafted EVA film retains a certain fluidity, which facilitates the bonding with the glass in the subsequent lamination process.

[0048] Optionally, the photoinitiator is selected from one or more of photoinitiator 184D, photoinitiator 651, photoinitiator TPO and photoinitiator 819.

[0049] By adopting the above technical solution, a photoinitiator is selected and added to the reaction system. On the one hand, it can promote the cross-linking reaction during the pre-cross-linking process. On the other hand, in the subsequent process of laminating the laminated glass, the performance of the photoinitiator can be used to promote the further cross-linking reaction of the pre-cross-linked grafted EVA film, thereby solidifying the grafted EVA film.

[0050] Optionally, the auxiliary cross-linking agent is selected from one or more of trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, ethoxylated trimethylolpropane triacrylate and pentaerythritol triacrylate.

[0051] By adopting the above technical solution, multifunctional acrylate substances are selected as auxiliary cross-linking agents, which is conducive to the occurrence of cross-linking reactions between grafted EVA molecules, making the pre-cross-linking degree of the pre-cross-linked grafted EVA film controllable, and facilitating the subsequent lamination process of laminated glass.

[0052] Optionally, the silane coupling agent is one or more of γ-methacryloxypropyltrichlorosilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane.

[0053] By adopting the above technical solution and selecting a methacryloyloxyalkyl silane coupling agent, it is beneficial to improve the adhesive properties of the pre-crosslinked grafted EVA film.

[0054] Optionally, the pre-crosslinking degree of the pre-crosslinked grafted EVA film is 0.1-20%.

[0055] By adopting the above technical solution and controlling the pre-crosslinking degree, the pre-crosslinked grafted EVA film can be cured to a certain extent while retaining good fluidity, thereby improving the weather resistance of the pre-crosslinked grafted EVA film and facilitating lamination with glass.

[0056] In a fourth aspect, the present application provides a process for preparing a pre-crosslinked grafted EVA film, which adopts the following technical solution: A process for preparing a pre-crosslinked grafted EVA film, comprising the following steps:

[0057] P1. Prepare raw materials according to the ratio, stir and mix the raw materials required for the pre-crosslinked grafted EVA film to obtain mixture B;

[0058] P2, adding mixture B into a screw extruder, extruding through a T-shaped flat die, casting, cooling and shaping to obtain a grafted EVA film to be treated;

[0059] P3. Irradiate the grafted EVA film to be treated to obtain a pre-crosslinked grafted EVA film.

[0060] By adopting the above technical solution, the raw materials are mixed and extruded into a film through the mold of a screw extruder, which facilitates the subsequent preliminary curing of the film through pre-crosslinking. The grafted EVA molecules in the grafted EVA film to be treated undergo a cross-linking reaction under the action of radiation, and the co-crosslinking agent plays a promoting role, thereby obtaining a pre-cross-linked grafted EVA film.

[0061] Optionally, in step P3, the radiation is carried out using an electron beam.

[0062] By adopting the above technical solution, electron beam radiation cross-linking is suitable for materials with smaller thickness and regular shape. Therefore, in the radiation cross-linking reaction of the grafted EVA film, the effect of using electron beam is better.

[0063] Optionally, in the P3 step, the radiation dose is 40-80 kGy.

[0064] By adopting the above technical solution and controlling the radiation dose, the pre-crosslinking degree of the pre-crosslinked grafted EVA film can be controlled.

[0065] In a fifth aspect, the present application provides a process for laminating laminated glass, which adopts the following technical solution:

[0066] A laminated glass lamination process comprises the following steps:

[0067] T1. Laying a pre-crosslinked grafted EVA film between two pieces of glass to obtain a laminated glass to be treated, evacuating the interior of the laminated glass to be treated using a vacuum ring, maintaining a vacuum degree of (-0.095)-(-0.09) MPa, heating and maintaining the temperature at 80-120° C. for 20-30 minutes to obtain a vacuum-heated laminated glass;

[0068] Among them, the vacuum ring refers to a sealing strip that is installed on the periphery of the laminated glass to be processed, so that the edge of the laminated glass to be processed is sealed, and the interior of the laminated glass to be processed is vacuumed through the exhaust pipe joint provided on the sealing strip.

[0069] By adopting the above technical solution, the interior of the laminated glass to be treated is evacuated by a vacuum ring, and then subjected to a heat treatment, so that the grafted EVA molecules continue to undergo a cross-linking reaction, and the grafted EVA film is further solidified, ultimately obtaining a laminated glass product with stable connections and low fogging resistance;

[0070] When ordinary EVA films are assembled, they usually need to be cured at above 130°C, and after roller pressing or vacuum heating treatment, they are placed in an autoclave for heat sealing. The curing temperature required for pre-crosslinked grafted EVA films is reduced to 80-120°C, and after vacuum and heating treatment, the autoclave treatment step can be omitted, which not only reduces the energy consumption of assembly, but also greatly shortens the time required for the assembly process and improves processing efficiency.

[0071] Optionally, after step T1, the following steps are further included:

[0072] T2: Irradiate the vacuum heated laminated glass with ultraviolet radiation at a dose of 10-200 Mj / m 2 , and obtain the UV-cured laminated glass.

[0073] By adopting the above technical solution, when a photoinitiator is used in the preparation process of the pre-crosslinked grafted EVA film, after the laminated glass is vacuumed and heated, the crosslinking degree of the grafted EVA film can be further improved by adding a step of ultraviolet irradiation, thereby improving the curing degree of the grafted EVA film. Without adding a photoinitiator, the final crosslinking degree of the grafted EVA film is in the range of 1%-20%, while after adding a photoinitiator, the final crosslinking degree of the grafted EVA film can reach 20%-60%.

[0074] Optionally, in step T1, a first layer of pre-cross-linked grafted EVA film, a dimming element and a second layer of pre-cross-linked grafted EVA film are sequentially laid between two pieces of glass.

[0075] Optionally, the dimming element is selected from one of a PDLC dimming film, an electrochromic (EC) element and a suspended particle device (SPD).

[0076] By adopting the above technical solution, the dimming element is set to make the laminated glass into dimming glass. The dimming element is set between two pieces of glass and bonded to the glass through a pre-crosslinked grafted EVA film, thereby obtaining a dimming glass with a stable connection and not easy to generate fog.

[0077] Since the curing temperature of ordinary EVA film is usually above 130℃, the PVB film commonly used in dimming glass also needs to be laminated at above 130℃. Under such temperature conditions, certain substances in the dimming components, such as the dyes and liquid crystals in the PDLC dimming film, are easily affected by temperature, resulting in reduced dimming performance and the risk of display function failure. The curing temperature required for pre-crosslinked grafted EVA film is 80-120℃, which is less likely to have an adverse effect on the performance of the dimming components, resulting in better performance of the dimming glass.

[0078] In a sixth aspect, the present application provides a process for laminating laminated glass, which adopts the following technical solution:

[0079] A laminated glass lamination process comprises the following steps:

[0080] Q1. Lay a pre-crosslinked grafted EVA film between two pieces of glass to obtain a laminated glass to be treated. Vacuum the interior of the laminated glass to be treated using a vacuum ring, maintaining a vacuum degree of (-0.095)-(-0.09) MPa. Heat and maintain the temperature at 80-120°C for 20-30 minutes to obtain a vacuum-heated laminated glass.

[0081] The vacuum ring refers to a sealing strip that is placed around the periphery of the laminated glass to be processed, so that the edge of the laminated glass to be processed is sealed, and the interior of the laminated glass to be processed is vacuumed through the exhaust pipe joint provided on the sealing strip;

[0082] Q2. Place the vacuum-heated laminated glass into an autoclave for heat-sealing treatment. Maintain the autoclave pressure at 0.1-0.5 MPa and the autoclave temperature at 80-120°C. After treating for 40-60 minutes, take it out to obtain the heat-sealed laminated glass.

[0083] By adopting the above technical solution, the adhesion between the glass and the pre-crosslinked grafted EVA film is enhanced through vacuuming and heating treatment, and then placed in an autoclave at a temperature of 80-120°C, a cross-linking reaction continues to occur between the grafted EVA molecules, and finally a laminated glass product with stable connection and non-fogging is obtained. The autoclave treatment can improve the curing degree of the grafted EVA film. However, even if the autoclave step is not adopted, sufficient bonding strength can be achieved between the glass and the grafted EVA film after the treatment in step Q1.

[0084] When ordinary EVA films are laminated, they usually need to be cured at a temperature above 130°C, and the pressure of the autoclave needs to be set at 1.2-1.4MPa. However, the curing temperature and pressure required for pre-crosslinked grafted EVA films are lower, thereby reducing the energy consumption of the laminated glass lamination process and improving processing efficiency.

[0085] Optionally, after step Q2, the following steps are further included:

[0086] Q3. Irradiate the laminated glass after heat sealing with ultraviolet light, the ultraviolet dose is 10-200Mj / m 2 , and obtain the UV-cured laminated glass.

[0087] By adopting the above technical solution, when a photoinitiator is used in the preparation process of the pre-crosslinked grafted EVA film, after the laminated glass is heat-sealed in an autoclave, the crosslinking degree of the grafted EVA film can be further improved by adding a step of ultraviolet irradiation, thereby improving the curing degree of the grafted EVA film.

[0088] Optionally, in the step Q1, a first layer of pre-cross-linked grafted EVA film, a dimming element and a second layer of pre-cross-linked grafted EVA film are sequentially laid between the two pieces of glass.

[0089] Optionally, the dimming element is selected from one of a PDLC dimming film, an electrochromic (EC) element and a suspended particle device (SPD).

[0090] By adopting the above technical solution, the dimming element is set to make the laminated glass into dimming glass. The dimming element is set between two pieces of glass and bonded to the glass through a pre-crosslinked grafted EVA film, thereby obtaining a dimming glass with a stable connection and not easy to generate fog.

[0091] Since the curing temperature of ordinary EVA film is usually above 130℃, the PVB film commonly used in dimming glass also needs to be laminated at above 130℃. Under such temperature conditions, certain substances in the dimming components, such as the dyes and liquid crystals in the PDLC dimming film, are easily affected by temperature, resulting in reduced dimming performance and the risk of display function failure. The curing temperature required for pre-crosslinked grafted EVA film is 80-120℃, which is less likely to have an adverse effect on the performance of the dimming components, resulting in better performance of the dimming glass.

[0092] In a seventh aspect, the present application provides a laminated glass, which adopts the following technical solution:

[0093] A laminated glass is produced by the lamination process of laminated glass described in any one of the following methods 1-6:

[0094] Method 1:

[0095] Laying a pre-crosslinked grafted EVA film between two pieces of glass to obtain a laminated glass to be treated, evacuating the interior of the laminated glass to be treated by a vacuum ring, maintaining a vacuum degree of (-0.095)-(-0.09) MPa, heating and maintaining the temperature at 80-120° C. for 20-30 minutes to obtain a vacuum-heated laminated glass;

[0096] Method 2:

[0097] The pre-crosslinked grafted EVA film is laid between two pieces of glass to obtain a laminated glass to be treated. The interior of the laminated glass to be treated is evacuated by a vacuum ring, and the vacuum degree is maintained at (-0.095)-(-0.09) MPa. The laminated glass is heated and maintained at a temperature of 80-120°C for 20-30 minutes to obtain a laminated glass after vacuum heating. The laminated glass after vacuum heating is irradiated with ultraviolet light at a dose of 10-200 Mj / m 2 , obtaining UV-cured laminated glass;

[0098] Method 3:

[0099] A first layer of pre-crosslinked grafted EVA film, a dimming element, and a second layer of pre-crosslinked grafted EVA film are sequentially laid between two pieces of glass to obtain a laminated glass to be treated. The interior of the laminated glass to be treated is evacuated using a vacuum ring, with the vacuum degree maintained at (-0.095)-(-0.09) MPa. The laminated glass is heated and maintained at a temperature of 80-120°C for 20-30 minutes to obtain a vacuum-heated laminated glass.

[0100] Method 4:

[0101] Laying a pre-crosslinked grafted EVA film between two pieces of glass to obtain a laminated glass to be processed, evacuating the interior of the laminated glass to be processed by a vacuum ring, maintaining a vacuum degree at (-0.095)-(-0.09) MPa, heating and maintaining the temperature at 80-120° C. for 20-30 minutes to obtain a laminated glass after vacuum heating, placing the laminated glass after vacuum heating in an autoclave for heat sealing treatment, maintaining the pressure of the autoclave at 0.1-0.5 MPa and the temperature of the autoclave at 80-120° C. for 40-60 minutes, and removing the laminated glass after heat sealing.

[0102] Method 5:

[0103] A pre-crosslinked grafted EVA film is laid between two pieces of glass to obtain a laminated glass to be treated. The interior of the laminated glass to be treated is evacuated by a vacuum ring, and the vacuum degree is maintained at (-0.095)-(-0.09) MPa. The laminated glass is heated and maintained at a temperature of 80-120°C. After treatment for 20-30 minutes, a vacuum-heated laminated glass is obtained. The vacuum-heated laminated glass is placed in an autoclave for heat sealing treatment. The pressure of the autoclave is maintained at 0.1-0.5 MPa, and the temperature of the autoclave is maintained at 80-120°C. After treatment for 40-60 minutes, the laminated glass is taken out to obtain a heat-sealed laminated glass. The heat-sealed laminated glass is irradiated with ultraviolet light at a dose of 10-200 Mj / m 2 , obtaining UV-cured laminated glass;

[0104] Method 6:

[0105] Laying a first layer of pre-crosslinked grafted EVA film, a dimming element, and a second layer of pre-crosslinked grafted EVA film between two pieces of glass in sequence to obtain a laminated glass to be processed; evacuating the interior of the laminated glass to be processed by a vacuum ring, maintaining a vacuum degree at (-0.095)-(-0.09) MPa; heating and maintaining the temperature at 80-120° C. for 20-30 minutes to obtain a vacuum-heated laminated glass; placing the vacuum-heated laminated glass in an autoclave for heat sealing, maintaining the pressure of the autoclave at 0.1-0.5 MPa and the temperature of the autoclave at 80-120° C. for 40-60 minutes to obtain a heat-sealed laminated glass;

[0106] By adopting the above technical solution, laminated glass is produced by pre-crosslinking and grafting EVA film. Since hydrophilic groups are introduced into the EVA molecules, when water vapor enters from the edge of the laminated glass, the hydrophilic groups on the grafted EVA molecules can combine with water molecules, thereby improving the defect of easy fogging at the edge of the laminated glass.

[0107] In summary, this application includes at least one of the following beneficial technical effects:

[0108] 1. Under the action of the grafting initiator, EVA and the hydrophilic modifier undergo a grafting reaction, introducing hydrophilic groups into the EVA molecular chain. The hydrophilically modified grafted EVA particles are then made into a grafted EVA film and applied to laminated glass. When water vapor enters from the edge of the glass, the hydrophilic groups introduced into the EVA molecules can combine with the water molecules, making it difficult for the water vapor in the laminated glass to aggregate into droplets, thus improving the defect of easy fogging at the edge of the laminated glass.

[0109] 2. The grafted EVA film has a certain degree of crosslinking through the crosslinking reaction. On the one hand, it improves the stability and weather resistance of the grafted EVA film. When used in the lamination process of laminated glass, the size and shape of the pre-crosslinked grafted EVA film are not easily changed, reducing the defective rate of laminated glass. On the other hand, by controlling the pre-crosslinking degree, the pre-crosslinked grafted EVA film retains a certain degree of fluidity, which facilitates bonding with the glass in the subsequent lamination process.

[0110] 3. When ordinary EVA films are laminated, they usually need to be cured at temperatures above 130°C, followed by roller pressing or vacuum heating, and then placed in an autoclave for heat sealing. However, the curing temperature required for pre-crosslinked grafted EVA films is reduced to 80-120°C. After vacuuming and heating, the autoclave step can be omitted. This not only reduces lamination energy consumption, but also significantly shortens the lamination process time, improving processing efficiency.

[0111] 4. When ordinary EVA films are laminated, they usually need to be cured at a temperature above 130°C, and the pressure of the autoclave needs to be set at 1.2-1.4MPa. However, the curing temperature and pressure required for pre-crosslinked grafted EVA films are lower, thereby reducing the energy consumption of the laminated glass lamination process and improving processing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] Figure 1 It is a structural diagram for illustrating the positional relationship between the laminated glass and the detection area in the application examples and comparative examples of the present application.

[0113] Description of the accompanying drawings: 1. Laminated glass; 11. Detection area. DETAILED DESCRIPTION

[0114] Source of raw materials

[0115] Unless otherwise specified, the raw material specifications and sources in the following preparation examples, embodiments, application examples and comparative examples are shown in Table 1 below.

[0116] raw material Specification source EVA VA content: 18%-40% Suzhou Lutuo Materials Co., Ltd. Polyhydroxyethyl methacrylate <![CDATA[P885046(Average M v = 20000)]]> Shanghai MacLean Biochemical Technology Co., Ltd.

[0117] Preparation Example

[0118] Preparation Example 1

[0119] A grafted EVA particle is prepared by the following steps:

[0120] S1. Weigh 300 g of EVA, 0.03 g of a vulcanizing agent DCP, and 1.5 g of hydroxyethyl methacrylate, wherein the VA content of the EVA is 18%, and stir the EVA, the vulcanizing agent DCP, and the hydroxyethyl methacrylate until they are fully mixed to obtain a mixture A.

[0121] S2. Add mixture A into a screw extruder for melt blending, extrusion, and granulation. The temperature of each zone of the screw extruder is controlled within the range of 160-180° C. and the screw speed of the screw extruder is 160 r / min to obtain grafted EVA particles.

[0122] Preparation Example 2-3

[0123] Preparation Example 2-3 differs from Preparation Example 1 in that the type and amount of the grafting initiator, the type and amount of the hydrophilic modifier, the VA content of the EVA, and the screw speed of the screw extruder are different, as shown in the following table:

[0124] Table 2 Preparation Examples 2-3

[0125]

[0126] Preparation Example 4-5

[0127] The difference between Preparation Example 4-5 and Preparation Example 3 is that the type of hydrophilic modifier and the VA content of EVA are different, as shown in the following table:

[0128] Preparation Example Preparation Example 4 Preparation Example 5 VA content of EVA 33％ 40％ Types of hydrophilic modifiers 2-Ethyl methacrylate sodium salt Hydroxypropyl methacrylate

[0129] Example

[0130] Example 1

[0131] A pre-crosslinked grafted EVA film is prepared by the following steps:

[0132] P1. Weigh 200 g of the grafted EVA particles obtained in Preparation Example 1, 0.2 g of trimethylolpropane trimethacrylate, and 0.2 g of γ-mercaptopropyltrimethoxysilane, and stir the grafted EVA particles, trimethylolpropane trimethacrylate, and γ-mercaptopropyltrimethoxysilane until fully mixed to obtain a mixture B.

[0133] P2. Add mixture B to a screw extruder, control the temperature of each zone of the screw extruder within the range of 75-90° C., and operate the screw extruder at a speed of 200 r / min. Extrude the mixture through a T-shaped flat die, cast the mixture, cool it, and shape it to obtain a grafted EVA film to be treated;

[0134] P3. Irradiate the grafted EVA film to be treated by electron beam with a radiation dose of 60 kGy to obtain a pre-crosslinked grafted EVA film.

[0135] Example 2-3

[0136] The difference between Example 2-3 and Example 1 is that the source of the grafted EVA particles, the type and amount of the co-crosslinking agent, the type and amount of the silane coupling agent, the screw speed of the screw extruder, and the radiation dose of the electron beam are different, as shown in the following table:

[0137] Example Example 2 Example 3 Source of grafted EVA particles Preparation Example 2 Preparation Example 3 Types of cross-linking agents Tris(2-hydroxyethyl)isocyanurate triacrylate Pentaerythritol triacrylate Amount of cross-linking agent 2g 4g Types of silane coupling agents γ-Methacryloyloxypropyltrichlorosilane γ-Mercaptopropyltriethoxysilane Dosage of silane coupling agent 1g 2g Screw speed of screw extruder 150r / min 300r / min Electron beam radiation dose 40 kGy 80kGy

[0138] Example 4

[0139] A pre-crosslinked grafted EVA film is prepared by the following steps:

[0140] P1. Weigh 200 g of the grafted EVA particles obtained in Preparation Example 4, 0.5 g of photoinitiator 184D, 0.5 g of photoinitiator 651, 0.1 g of trimethylolpropane triacrylate, 0.1 g of ethoxylated trimethylolpropane triacrylate, 0.1 g of γ-methacryloyloxypropyltrimethoxysilane, and 0.1 g of γ-mercaptopropyltrimethoxysilane; and stir the grafted EVA particles, photoinitiator 184D, photoinitiator 651, trimethylolpropane triacrylate, and γ-mercaptopropyltrimethoxysilane until thoroughly mixed to obtain a mixture B.

[0141] P2. Add mixture B to a screw extruder, control the temperature of each zone of the screw extruder within the range of 75-90° C., and rotate the screw of the screw extruder at a speed of 220 r / min. Extrude the mixture through a T-shaped flat die, cast the mixture, cool it, and then shape it to obtain a grafted EVA film to be treated;

[0142] P3. Irradiate the grafted EVA film to be treated by electron beam with a radiation dose of 60 kGy to obtain a pre-crosslinked grafted EVA film.

[0143] Examples 5-6

[0144] The difference between Example 5-6 and Example 4 is that the source of the grafted EVA particles, the type and amount of the photoinitiator, the type and amount of the co-crosslinking agent, and the type and amount of the silane coupling agent are different, as shown in the following table:

[0145] Table 5 Examples 5-6

[0146]

[0147]

[0148] Application Examples

[0149] The glass used in the following application examples has a size of 100 mm × 100 mm × 5 mm, and the pre-crosslinked grafted EVA film and PDLC dimming film have a size of 100 mm × 100 mm.

[0150] Application Example 1

[0151] A laminated glass is made by the following steps:

[0152] The pre-crosslinked grafted EVA film obtained in Example 1 was laid between two pieces of glass to obtain a laminated glass to be treated. The interior of the laminated glass to be treated was evacuated using a vacuum ring, with the vacuum degree maintained at -0.095 MPa. The laminated glass was heated and maintained at 80° C. for 30 minutes to obtain a vacuum-heated laminated glass.

[0153] Among them, the vacuum ring refers to a sealing strip that is installed on the periphery of the laminated glass to be processed, so that the edge of the laminated glass to be processed is sealed, and the interior of the laminated glass to be processed is vacuumed through the exhaust pipe joint provided on the sealing strip.

[0154] Application Example 2

[0155] A first layer of pre-crosslinked grafted EVA film, a PDLC dimming film, and a second layer of pre-crosslinked grafted EVA film were sequentially laid between two pieces of glass, wherein the first layer of pre-crosslinked grafted EVA film and the second layer of pre-crosslinked grafted EVA film were both the pre-crosslinked grafted EVA films obtained in Example 2, to obtain a laminated glass to be treated. The interior of the laminated glass to be treated was vacuumed by a vacuum ring, and the vacuum degree was maintained at -0.09 MPa. The laminated glass was heated and the temperature was maintained at 120°C. After treatment for 30 minutes, a vacuum-heated laminated glass was obtained.

[0156] Application Example 3

[0157] A laminated glass is made by the following steps:

[0158] T1. Laying the pre-crosslinked grafted EVA film obtained in Example 4 between two pieces of glass to obtain laminated glass to be treated, evacuating the interior of the laminated glass to be treated using a vacuum ring, maintaining the vacuum degree at -0.093 MPa, and heating and maintaining the temperature at 90° C. for 28 minutes to obtain vacuum-heated laminated glass;

[0159] T2: Irradiate the vacuum heated laminated glass with ultraviolet light at a dose of 10Mj / m 2 , and obtain the UV-cured laminated glass.

[0160] Application Example 4

[0161] T1. Laying a first layer of pre-crosslinked grafted EVA film, a PDLC dimming film, and a second layer of pre-crosslinked grafted EVA film between two pieces of glass, wherein both the first layer of pre-crosslinked grafted EVA film and the second layer of pre-crosslinked grafted EVA film are the pre-crosslinked grafted EVA films obtained in Example 5, to obtain a laminated glass to be treated. Vacuuming the interior of the laminated glass to be treated using a vacuum ring, maintaining a vacuum degree at -0.09 MPa, and heating the laminated glass at 90° C. for 25 minutes to obtain a vacuum-heated laminated glass.

[0162] T2: Irradiate the vacuum heated laminated glass with ultraviolet light at a dose of 100Mj / m 2 , and obtain the UV-cured laminated glass.

[0163] Application Example 5

[0164] A laminated glass is made by the following steps:

[0165] Q1. The pre-crosslinked grafted EVA film obtained in Example 1 was laid between two pieces of glass to obtain laminated glass to be treated. The interior of the laminated glass to be treated was evacuated using a vacuum ring, with the vacuum degree maintained at -0.095 MPa. The laminated glass was heated and maintained at 80°C for 25 minutes to obtain vacuum-heated laminated glass.

[0166] The vacuum ring refers to a sealing strip that is placed around the periphery of the laminated glass to be processed, so that the edge of the laminated glass to be processed is sealed, and the interior of the laminated glass to be processed is vacuumed through the exhaust pipe joint provided on the sealing strip;

[0167] Q2. Place the laminated glass after vacuum heating in an autoclave for heat sealing treatment. The pressure of the autoclave is maintained at 0.1 MPa and the temperature of the autoclave is maintained at 90°C. After treating for 50 minutes, take it out to obtain the heat-sealed laminated glass.

[0168] Application Example 6

[0169] A laminated glass is made by the following steps:

[0170] Q1. Laying a first layer of pre-crosslinked grafted EVA film, a PDLC dimming film, and a second layer of pre-crosslinked grafted EVA film between two pieces of glass, wherein the first layer of pre-crosslinked grafted EVA film and the second layer of pre-crosslinked grafted EVA film are both the pre-crosslinked grafted EVA films obtained in Example 3, to obtain a laminated glass to be treated. Vacuuming the interior of the laminated glass to be treated using a vacuum ring, maintaining a vacuum degree of -0.093 MPa, and heating and maintaining the temperature at 100° C. for 25 minutes to obtain a vacuum-heated laminated glass.

[0171] Q2. Place the laminated glass after vacuum heating in an autoclave for heat sealing treatment. The pressure of the autoclave is maintained at 0.3 MPa and the temperature of the autoclave is maintained at 120°C. After treating for 40 minutes, take it out to obtain the heat-sealed laminated glass.

[0172] Application Example 7

[0173] A laminated glass is made by the following steps:

[0174] Q1. The pre-crosslinked grafted EVA film obtained in Example 4 was laid between two pieces of glass to obtain laminated glass to be treated. The interior of the laminated glass to be treated was evacuated using a vacuum ring, with the vacuum degree maintained at -0.09 MPa. The laminated glass was heated and maintained at 120° C. for 20 minutes to obtain vacuum-heated laminated glass.

[0175] Q2. Place the laminated glass after vacuum heating into an autoclave for heat sealing treatment. The pressure of the autoclave is maintained at 0.5 MPa and the temperature of the autoclave is maintained at 80°C. After the treatment for 60 minutes, the laminated glass is taken out to obtain the heat-sealed laminated glass.

[0176] Q3. Irradiate the laminated glass after heat sealing with ultraviolet light, the ultraviolet dose is 100Mj / m 2 , and obtain the UV-cured laminated glass.

[0177] Application Example 8

[0178] A laminated glass is made by the following steps:

[0179] Q1. Laying a first layer of pre-crosslinked grafted EVA film, a PDLC dimming film, and a second layer of pre-crosslinked grafted EVA film between two pieces of glass, wherein both the first layer of pre-crosslinked grafted EVA film and the second layer of pre-crosslinked grafted EVA film are the pre-crosslinked grafted EVA films obtained in Example 6, to obtain a laminated glass to be treated. The interior of the laminated glass to be treated was evacuated using a vacuum ring, with the vacuum maintained at -0.095 MPa. The laminated glass was heated and maintained at 100° C. for 20 minutes to obtain a vacuum-heated laminated glass.

[0180] Q2. Place the laminated glass after vacuum heating into an autoclave for heat sealing treatment. The pressure of the autoclave is maintained at 0.3 MPa and the temperature of the autoclave is maintained at 90°C. After the treatment for 50 minutes, the laminated glass is taken out to obtain the heat-sealed laminated glass.

[0181] Q3. Irradiate the laminated glass after heat sealing with ultraviolet light, the ultraviolet dose is 200Mj / m 2 , and obtain the UV-cured laminated glass.

[0182] Comparative Examples The glass used in the following comparative examples all has a size of 100 mm×100 mm×5 mm, and the sizes of the grafted EVA film to be treated, the pre-crosslinked grafted EVA film, the commercially available EVA film and the PDLC dimming film all have a size of 100 mm×100 mm.

[0183] Comparative Example 1

[0184] A laminated glass is made by the following steps:

[0185] R1. Lay a commercially available EVA film between two pieces of glass to obtain a laminated glass to be processed, and roll the laminated glass to be processed using a squeeze roller. The rolling pressure is maintained at 1.2 MPa and the temperature is maintained at 130°C to obtain a rolled laminated glass. R2. Place the rolled laminated glass into an autoclave for heat sealing treatment. The pressure of the autoclave is maintained at 1.4 MPa and the temperature of the autoclave is maintained at 140°C. After treatment for 60 minutes, the glass is taken out to obtain a heat-sealed laminated glass.

[0186] Comparative Example 2

[0187] The difference between Comparative Example 2 and Comparative Example 1 is that in step R1, a first layer of commercially available EVA film, a PDLC dimming film, and a second layer of commercially available EVA film are sequentially laid between two pieces of glass.

[0188] Comparative Example 3

[0189] The difference between Comparative Example 3 and Application Example 5 is that in Comparative Example 3, when preparing the grafted EVA particles for obtaining the pre-crosslinked grafted EVA film, butyl methacrylate of the same mass is used instead of hydroxyethyl methacrylate.

[0190] Comparative Example 4

[0191] The difference between Comparative Example 4 and Application Example 5 is that in Comparative Example 4, when preparing the grafted EVA particles for obtaining the pre-crosslinked grafted EVA film, polyhydroxyethyl methacrylate of the same mass is used instead of hydroxyethyl methacrylate.

[0192] Comparative Example 5

[0193] The difference between Comparative Example 5 and Application Example 5 is that in Comparative Example 5, when preparing the grafted EVA particles for preparing the pre-crosslinked grafted EVA film, pentaerythritol triacrylate of the same mass is used instead of hydroxyethyl methacrylate.

[0194] Comparative Example 6

[0195] The difference between Comparative Example 6 and Application Example 5 is that, in step Q1, the grafted EVA film to be treated obtained in Example 1 is used instead of the pre-crosslinked grafted EVA film obtained in Example 1.

[0196] Performance testing

[0197] Detection method

[0198] The laminated glass obtained according to the corresponding use case and comparative example of GB / T2410-2008 was subjected to haze test, and the laminated glass was placed in a constant temperature and humidity test chamber for a damp heat aging test, and was taken out after being kept at 85°C and 85% humidity for 1000 hours.

[0199] Reference Figure 1The laminated glass 1 includes a detection area 11, which is in the shape of a square. The outer edge of the detection area 11 coincides with the edge of the laminated glass 1. The longitudinal section of the outer edge of the detection area 11 is a square, the longitudinal section of the inner edge of the detection area 11 is a square, and the distance between the outer edge of the detection area 11 and the inner edge of the detection area 11 is 10 mm.

[0200] The haze tester was used to measure the haze of the test area of each laminated glass. The laminated glass with PDLC dimming film (Application Example 2, Application Example 4, Application Example 6, Application Example 8 and Comparative Example 2) needed to be powered on when measuring the haze. The power supply voltage was 48V and the current was 2A.

[0201] The haze test results of the laminated glass in Application Examples 1-8 are shown in Table 6.

[0202] Application Examples Haze 1 0.9％ 2 0.8％ 3 0.6％ 4 0.7％ 5 0.8％ 6 0.8％ 7 0.6％ 8 0.7％

[0203] The haze test results of the laminated glass in Comparative Examples 1-6 are shown in Table 7.

[0204] Comparative Example Haze 1 65.1％ 2 67.8％ 3 65.4％ 4 32.5％ 5 13.8％ 6 5.2％

[0205] From the combination of Application Examples 1-8 and Comparative Examples 1-2 and Tables 6-7, it can be seen that the pre-cross-linked grafted EVA film made by grafting EVA particles can effectively improve the defect of poor hydrophilicity of EVA, which leads to the generation of fog after water vapor enters the laminated glass, when used in the lamination process of laminated glass.

[0206] Combining Application Examples 1-8 with Comparative Example 3 and Tables 6-7, it can be seen that although EVA was also grafted in Comparative Example 3, butyl methacrylate does not contain a hydrophilic group, resulting in the laminated glass obtained in Comparative Example 3 being prone to fogging at the edges. Therefore, introducing hydrophilic groups onto the EVA molecular chains by grafting can effectively improve the defect of prone fogging at the edges of laminated glass.

[0207] Combining Application Examples 1-8 and Comparative Examples 4-5 with Tables 6-7, it can be seen that the anti-fogging performance of the edge of the laminated glass obtained in Comparative Example 4-5 is inferior to that of the laminated glass obtained in Application Examples 1-8. This is because the hydrophilic modifier selected in Comparative Examples 4-5 contains multiple carbon-carbon double bonds in its molecular chain. During the grafting reaction, not only a grafting reaction occurs between the EVA and the hydrophilic modifier, but also a three-dimensional cross-linking reaction occurs, which reduces the fluidity of the grafted EVA particles and thus reduces the fluidity of the pre-cross-linked grafted EVA film, which has a certain impact on the lamination of the laminated glass. Therefore, it is best to use a hydrophilic modifier containing only one carbon-carbon double bond in its molecular chain.

[0208] The anti-fogging performance of the edge of the laminated glass obtained in Comparative Example 4 is inferior to that of the laminated glass obtained in Comparative Example 5. This is because the hydrophilic modifier used in Comparative Example 4 is a polymer, while the hydrophilic modifier used in Comparative Example 5 is a monomer. During the grafting reaction, a three-dimensional cross-linking reaction is more likely to occur in the system of Comparative Example 4, and the resulting grafted EVA particles have lower fluidity, thereby causing a greater negative impact on the lamination of the laminated glass.

[0209] Combining Application Examples 1-8 and Comparative Example 6 and Tables 6-7, it can be seen that the anti-fogging performance of the edge of the laminated glass obtained in Comparative Example 6 is slightly lower than that of the laminated glass obtained in Application Examples 1-8. This is because the grafted EVA film in Comparative Example 6 was not pre-crosslinked, resulting in excessive fluidity of the grafted EVA film, which had a certain impact on the lamination of the laminated glass.

[0210] From Application Examples 1-8 and Table 6, it can be seen that the pre-crosslinked grafted EVA film made by hydrophilically modified grafted EVA particles can effectively improve the defect of fogging at the edge of laminated glass, and can be used in the preparation of dimming glass. Since the curing temperature of the pre-crosslinked grafted EVA film is lower, the pre-crosslinked grafted EVA film is more suitable for the lamination of dimming glass than the unmodified EVA film, and is less likely to affect the display performance of dimming elements such as PDLC dimming film. In addition, the addition of a photoinitiator during the preparation of the pre-crosslinked grafted EVA film is beneficial to the further curing of the pre-crosslinked grafted EVA film when the laminated glass is laminated. However, even without the addition of a photoinitiator, the laminated glass made from the pre-crosslinked grafted EVA film still has sufficiently excellent anti-fog performance.

[0211] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A pre-crosslinked grafted EVA film, characterized in that: The raw materials are prepared, and the components are as follows in parts by weight: The raw materials for preparing the grafted EVA particles include the following components in parts by weight: EVA 100 pieces Graft initiator 0.01-0.1 parts 0.5-5 parts of hydrophilic modifier; And it is prepared by the following method: S1. Prepare raw materials according to the ratio, stir and mix the raw materials required for grafting EVA particles to obtain mixture A; S2, adding mixture A into a screw extruder for melt blending, extrusion, and granulation to obtain grafted EVA particles; Wherein, the hydrophilic modifier is represented by the following chemical formula 1: Chemical formula one: Wherein, X1 is one of a hydrogen atom, a methyl group and an ethyl group, X2 is a C1-C6 divalent saturated hydrocarbon group, and R is selected from one of the following groups: (1) R is one of carboxyl, sulfonic acid and hydroxyl groups; Or (2) R is represented by the following chemical formula 2: Chemical formula 2: wherein Y1 and Y2 are the same or different and are each independently selected from a hydrogen atom, a methyl group and an ethyl group; or (3) R is represented by the following chemical formula 3: Chemical formula 3: Or (4) R is represented by the following chemical formula 4: Chemical formula 4: wherein Z is one of chlorine, bromine and iodine; The mass percentage of VA in the EVA is 18%-40%.

2. The pre-crosslinked grafted EVA film according to claim 1, characterized in that: The photoinitiator is selected from one or more of photoinitiator 184D, photoinitiator 651, photoinitiator TPO and photoinitiator 819.

3. The pre-crosslinked grafted EVA film according to claim 1, characterized in that: The pre-crosslinking degree of the pre-crosslinked grafted EVA film is 0.1-20%.

4. The process for preparing the pre-crosslinked grafted EVA film according to any one of claims 1 to 3, characterized in that: The following steps are involved: P1. Prepare raw materials according to the ratio, stir and mix the raw materials required for the pre-crosslinked grafted EVA film to obtain mixture B; P2, adding mixture B into a screw extruder, extruding through a T-shaped flat die, casting, cooling and shaping to obtain a grafted EVA film to be treated; P3. Irradiate the grafted EVA film to be treated to obtain a pre-crosslinked grafted EVA film.

5. A laminated glass lamination process, characterized in that: The following steps are involved: T1. Lay the pre-crosslinked grafted EVA film described in any one of claims 1 to 3 or the pre-crosslinked grafted EVA film prepared by the preparation process of the pre-crosslinked grafted EVA film described in claim 4 between two pieces of glass to obtain a laminated glass to be treated. Vacuum the interior of the laminated glass to be treated, heat it and maintain the temperature at 80-120° C. to obtain a vacuum-heated laminated glass.

6. The laminated glass lamination process according to claim 5, characterized in that: After the T1 step, the method further comprises the following steps: T2. Irradiating the vacuum-heated laminated glass with ultraviolet light to obtain UV-cured laminated glass.

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